A person knows the house so well - idiom

Hello,
Hope everyone is doing great.

Could you please help me find expressions or idioms that describe this situation,
An owner of the house knows everything in it, he sees and hears everything.

Thanks in advance,

Besbesnao said:

The owner of the house knows everything in it. He sees and hears everything.

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I'm not sure I understand that. In fact, I'm pretty sure I don't understand it.

Tarheel said:

I'm not sure I understand that. In fact, I'm pretty sure I don't understand it.

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I mean, in this context, the person knows what happens in every corner of their house; what comes, and what goes, and what is being said.

I can't think of any phrase that covers that situation. If you'd simply said that they know every corner of their house well, I'd have said use "He knows the house like the back of his hand", but that has nothing to do with things coming, going or being said. The only way to express that is to say "He knows absolutely everything that happens in the house" but there's no idiom involved there.

I guess if you live by yourself you can know everything that goes on in the house. Otherwise, not so much.