The B10k potentiometer has three terminals. The first one is used for ground, and the other two are used for input and output. If wired correctly you can read the difference in potential (volts) across the input and output of the potentiometer.

 

 

Wiring it up

To wire up this potentiometer, make sure to wire pin one (leftmost pin if the knob is pointing to the sky) to ground. You can wire the VCC out of your microcontroller to the second pin on the potentiometer, and the third pin to an input pin of your microcontroller. You can measure the difference from 5V (or 3.3V depending on your microcontroller) to determine how far the potentiometer has turned.