Might be in your recently called log. If you used cell phone and deleted your log, you can get it from your carrier.
If you still have the number you should leave message telling person that school security has it.
Usually school security don't have the resources to make sure each device is returned. The lost devices just sit in a box, and eventually get donated.
That is true. Yeah I have not deleted my call log. May give it a try, but if the owner is not smart enough to put a phone number other than their own for the lost message. Not sure if they would be smart enough to know how to check voice messages remotely.