IRCC will know. They run your Biometrics against USA immigration system (that is the info sharing field shown in GCMS notes) and get every single info about you if any. Not just USA but the 5 eye countries; USA, Australia, New Zealand and UK.
it’s up to decide if it is worth the risk. In my situation, I made an honest mistake and did not mention my UK visa refusal but I informed them visa web form as soon as I noticed the mistake and they asked me to adjust my study permit application accordingly and re-share it with them via email. Whatever you decide to do, good luck.