What way(s) are there to see what's behind windows curtain?

Are there any method to see behind the curtain? I feel that I have been spy by some assholes, but I have put double layers curtain. But why are they still seeing me? Such that they horn their motorbike when I entered my room All The Freaking Time! Those assholes are just bullies BTW. PS: Can a Thermal imaging... show more Are there any method to see behind the curtain?

I feel that I have been spy by some assholes, but I have put double layers curtain. But why are they still seeing me? Such that they horn their motorbike when I entered my room All The Freaking Time!

Those assholes are just bullies BTW.

PS: Can a Thermal imaging camera see what's behind the curtain?
Update: I have fully analysed and the result shows I am not mentally ill. I am perfectly fine.
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