How do you crack combination locks by listening to them?

Answer 1

if you have something that can hear small sounds. Most combo locks are set to *click* when you turn to the next number in the combonation. Most have solved that problem by insulating the locking mechinism that controls that. But some of the cheaper combo locks you can still hear an audible click... very very faint but you can hear it if you listen.

Answer 2

The theory is that you can hear the tumblers inside dropping into place. Maybe in the old locks, but nowadays, good luck.