You should be able go to your high school guidance counselor and ask to see your student files. While you are there, ask what part of your files are sent to colleges. Ask, If I pull a senior prank and get caught, would that kind of bad behavior be reported. (Laugh when you say it.)
In all likelihood a teacher can’t report your cheating unless they confront you, you deserve a chance to defend yourself. If you cheated and there aren’t any repurcussions/punishment there probably won’t be anything in your “permanent record.” If it’s in there, and you can’t refuse to have it shared with colleges, use it for the teaching moment it was. Colleges like to know you learned your lesson in high school.