A pendulum is a divination tool. It taps into your inner truth and helps you gain clarity on decisions and directions. 
 
To calibrate the pendulum, hold it in your dominant hand, hold it over your palm and ask the pendulum to show you a 'yes'. It will begin to move in a direction. This is your 'yes'. 
 
Then ask it to show you a 'no'.  The direction it moves is your 'no.'
 
You can calibrate the pendulum to any answers - maybe, yes, no, do it, don't it - whatever you want it to tell you.
 
If at first it doesn't move, try grounding, breathing, and centering and try again.