Micro:bit Intruder Detection & Logging System

You are the chief scientist of the research and development division of the Meow Secret Service. One fine day the top agent in your agency comes seeking help & he is looking desperate. "I need something fast. I think someone has been entering my safe house while I am out on a mission. Is there a way to discreetly detect if anyone has broken into my premises through the main door? In other words, I need a silent tripwire system." Opening your drawer, you found your trustee Micro:bit & a strong piece of magnet.