Other forms: pickpockets
A pickpocket is a criminal who steals things from people's pockets or bags. Your grandmother might warn you to be on the lookout for pickpockets when you travel to Paris.
Pickpockets take advantage of crowded situations to slide wallets, phones, and cash out of victims' pockets, and when they do this, you can say that they pickpocket. Probably the most famous literary pickpocket is Charles Dickens' character The Artful Dodger, from "Oliver Twist." Before pickpocket was coined, around 1590, they were called pick-purses, for obvious reasons.