my question is how will the port of entry guys (CBSA) find out if I was living in a different province. Do they know if you I was working in a different province?
We are talking about landing. Landing is when you arrive in Canada for the first time with your PR visa. Your paperwork will indicate if you are a PNP applicant and of which province. If you land in another province, the immigration officer will realize that you are landing outside your PNP province. If you do that, they are instructed to ask you what your plans are. If you say that you are going directly to your PNP province and they believe you, that might be it. If you admit that you are not planning on going there, they will tell you that it is a condition of your PR and they may decide to withhold your PR card and notify the PNP you applied under. Your PNP might then call you for an interview to find out if you are at that point living in your PNP province or what your plans are. When you apply under PNP, you sign a document stating that you intend to settle in the PNP province. If you lie on this document, you are guilty of misrepresentation. When you commit misrepresentation at the time you apply for PR or when you land, they can revoke your PR.
As for people who already got their PR through PNP and decided to leave that province later, I have not heard of anyone who got in trouble for that but it is possible that might start to happen in the future. A few years ago, they were also not checking who was landing in their PNP province and who wasn't but one day they decided they wanted to start doing that. The document you sign for PNP doesn't give a minimum time you must stay but it is possible in the future if you apply to renew a PR card or apply for citizenship that if you came through PNP and are no longer living in that province that you will have to explain if you actually attempted to settle there and how long you stayed there for. Therefore, I would advise anyone who applied through PNP to make an attempt to settle in their PNP province before moving somewhere else.