Everything is magnetic, only strong and weak. If the alarm is magnetic, you may or must have a ferromagnetic substance such as a magnetic card. Please look for it. Or the alarm is broken. It is photosensitive and has nothing to do with magnetism. You should think about whether you have been exposed to radioactive substances recently, or whether you have luminous substances (what people call luminous). We should be able to find out why.

Thanks for the supplement of sunfanyan4 downstairs.