Hopefully you did not install one of those cheap Chinese safes with a digital keypad (Harbor Freight, Amazon, Ebay, etc.). They use a spring loaded solenoid as part of the locking mechanism, and can be easily defeated. Simply striking the top of the safe or keypad area with your hand is enough to move the solenoid and open the safe.
I showed this method to a friend who had one of these safes. No tools needed. No sign of forced entry. He was not happy.