"I just heard you don't even know how to pick a lock! Go learn the basics." ― Vinny
The DIY Simple Lockpick kit consists of a bobby pin and flathead screwdriver with a yellow handle. It is truly good for only the simplest of locks, which are pretty frequent early on in the game.
The simple lockpick minigame in Thief Simulator works the same as in many games with a similar interface: The bobby pin needs to be angled in a specific way, then the screw driver is used to turn the lock. If successful, the lock clicks and the door/gate can be opened. If unsuccessful, the bobby pin rattles. The lock can be turned more if the bobby pin is angled close to the "sweet spot," and less if it is way off.
Players should be aware that the DIY Simple Lockpick has a high chance of breaking after multiple uses. It is highly recommended that the thief carries at least two at all times.
If a tenant wanders through a door/gate that has been unlocked, they will call the police.