You might be able to use a "wireless doorebell". Put the bell in your bedroom and mount the button in the door such that it will be pressed when the lock is opened. If you have the doors locked when you are driving and parked the battery in the button unit should last a good long time.
Does your care have a keyless entry system that opens the windows if you hold the button down? Accidental pressing of the button could explain most of the symptoms you see.