There are many ways to implement this feature. Most are done by simply wiring a plate with one nonconductive side and one conductive side. The nonconductive side is placed on the work surface and the conductive side will wire into the breakout board (or other location) and be configured as an input in Mach3/Mach4. Utilizing this feature requires a macro or a plugin.

For Mach4 users, check out the video below for an auto tool script example with tutorial: https://youtu.be/6-4JkDv9AgM