What is Capture chance on buildings

I don't know if Capture chance was in the base game. But I now see a Capture Chance on buildings now that I downloaded the CPP and the EUI. So I'm guessing it is a new thing.

What is the Capture chance and how does it affect me and the game?

Thanks.

Do you mean ConquestProb ?

ConquestProb is a % likelihood the building will survive the city being captured.