Can my parents equip my laptop that I bought with my own money with a surveillance system and timer?

Please answer

How old are you?

If you are under 18 years of age, then they can. It's not nice, but maybe you gave them enough reasons to do this.

OK,. This should explain what your parents did

As long as you are a minor, your parents / legal guardians may give you certain restrictions as part of their educational obligations, such as The setting up of a timer that you mentioned.

However, full monitoring could go too far, depending on age. Here, however, your previous behavior also depends on whether this justifies such monitoring.