New idiom related to surveillance: People do things, the sky watches
It might be:

人在做天在看
the people do, the Sky (God?) watches

or a more fluent translation

the Sky watches what the people do

The usage I'm aware of, in colloquial speech, is to describe some sort of karma, or payback from destiny if you do bad things and hope to get away with it.
For example:

You steal your friend's money
They suspect of you but can't prove it
They confront you about that
You deny everything
They say 人在做天在看

It's like, &quot;what goes around comes around&quot; in English.