Where can I get an ammonia sensor for guarding the entrance (and application features)?

Question

Electronics

Good afternoon!
Once again, our entrance was damaged by two-legged animals.
You need to take it red-handed - for example, make a loud siren on the ammonia sensor. Well, or at least a notification on a mobile phone in order to have time to quickly take some measures.
Ammonia sensors definitely exist in nature, but I could not find specific models and sellers. In elevators they say such things happen. Did you search badly?
Does anyone have experience with these types of sensors? Maybe there are features of their application or this approach is generally incorrect and there are some other ways? Cameras, please do not offer.
UPD: punishment is not included in the scope of the question, strictly automatic detection of the fact of vandalism.

Answer 1

It is necessary in a proven way - an inconspicuous piece of bare wire with a weak current)

Answer 2

I caught them twice, but unfortunately I didn’t manage to catch both of them red-handed, I just had to be deported. So, they were hardly able to read something. Although it might help in some cases ... I'll consider it, thanks.

Answer 3

Make transparent doors in the entrance, no one will go there because everything is visible.

Answer 4

How do they get to your door? We had an intercom installed, so the entrance became clean and fresh