My great-grandmother was deaf (since she was 10), and she knew if someone arrived after she went to bed (she was a farmer for much of her life, so she slept early).

How did she do it? Vibration. She could detect movement throughout the house. My great-uncle has a pretty good story of trying to sneak out/in after curfew.

So attach a motor connected to a smoke detector to the baseboard of a bed. For safety's sake, you'd use a pretty big motor. You'd also want to test it randomly.