What is a Mechanical Mouse?
A computer mouse with a metal or rubber ball on the underside is a mechanical mouse. The mouse's internal sensors detect any movement of the ball when it is rolled, and they change the mouse pointer on the screen to correspond. The underside of a mechanical mouse with the ball removed is shown in the image as an example.

In the modern era, the optical mouse has replaced this mouse. A mechanical mouse is vulnerable to having dust and other debris get on the ball and stop it from functioning.
The optical mouse has largely replaced the mechanical mouse. An input computer device called a mechanical mouse has a metal or rubber ball at the bottom. When the mouse is moved, the ball rolls and sensors inside the mouse track the movement and send signals to the pointer on the screen. A mechanical mouse is sometimes known as a ball mouse. Two wheels perpendicular to one another propel a ball within a mechanical mouse. These wheels are responsible for identifying the left-right and upward and downward movement of the ball and communicating that information to the cursor on the screen.

History of Mechanical Mouse
The mechanical mouse, which practically everyone used to interface with computers in the 1980s and 1990s, was the preferred device. In most cases, the mechanical mouse has been largely replaced as being outmoded by the portable and affordable optical mouse. They are similar in appearance and operation but rely on optical sensors instead of a ball because these are frequently more reliable.
On October 2, 1968, the German business Telefunken released a publication on their early ball mouse. The mouse made by Telefunken was offered as an add-on component for their computers. The ball mouse was developed in 1972 by Bill English, who also built Engelbart's initial mouse while employed by Xerox PARC.
The external wheels were swapped for a single rotating ball in the mouse. In the mouse's body, perpendicular chopper wheels chopped light beams as they traveled to light sensors, which detected the ball's motion. Throughout the 1980s and 1990s, this particular type of mouse resembled an upside-down trackball—it became the most frequently used with personal computers. It was included in the Xerox Alto computer's hardware bundle.
On the ball mouse, two rollers can freely rotate. They are 90 degrees apart. One roller detects the mouse's forward-backward and left-right movements. The ball is driven against the other two rollers by a third, 45-degree-angled, white roller that sits across from them and is spring-loaded. An encoder wheel with slotted edges that produces electrical pulses representing wheel movement is installed on the same shaft as each roller. On the disc of each wheel, a pair of light beams are placed so that when the other beam in the pair is approximately halfway between changes, the provided beam is interrupted or resumes freely passing light. Simple logic circuits interpret the relative time and determine which direction the wheel is rotating.
This incremental rotary encoder technique is also known as quadrature encoding of the wheel rotation due to the roughly quadrature phase of the data provided by the two optical sensors.
These signals are transmitted by the mouse through the mouse connection, as logic signals in ancient mice like the Xerox mice, and via a data-formatting IC in more current mice, to the computer system. The system's driver software transforms the signals into the mouse cursor's movement along the X and Y axes on the monitor.
The ball's surface is a precisely spherical rubber with a steel core. Given a suitable working surface beneath the mouse, the ball's weight creates a solid grip that correctly transmits mouse movement.
In 1975, Jack Hawley, doing business as The Mouse House in Berkeley, California, produced ball mice and wheel mice for Xerox. Based on another creation by Mouse House owner Jack Hawley, Honeywell created a different model of the mechanical mouse. It featured two moving wheels instead of a ball. Later, Key Tronic created a comparable product.
The "Analog mouse," a different mechanical mouse that is now usually regarded as obsolete, employs potentiometers rather than encoder wheels and is normally made to plug into an analog joystick. The most well-known example was the "Color Mouse," which RadioShack originally sold for their Color Computer (but which could also be used on MS-DOS computers with analog joystick ports, assuming the software allowed joystick input).