How to connect a "touch sense" pin to a analog or digital input
Some micro controllers will detect touch, However it will not be reliable as it relies upon the electrostatic charge of the person touching the fader. That is some what random. 

The capacitive sense pin on the fader is intended for connection to a Touch Circuit. This oscillates at a frequency determined by the capacitance connected to the Sense pin. Changes in the frequency caused by the additional capacitance of a person allow the circuit detect the Touch.  

The other problem of touching micro pins directly is the electrostatic charge of a normal person can kill the micro. Touch Sense circuit remove this problem by providing protection. Here are some examples you can buy, but there are plenty you can build your self.