I got 3 detentions total from freshman to junior year. It wasn’t anything serious at all. Our school gives 1 detention every time you’re more than 20 minutes late for a class. In all 3 cases, I was late because of public transportation delays. I know when my guidance counselor fills out my rec, he has to say whether or not I’ve ever received “disciplinary action.” Will he have to report the 3 detentions?
Unlikely, but it depends on the policy of your school.
However, and this is the important part, even if in the unlikely event that they were reported, colleges will not care.
Colleges are interested in disciplinary action that resulted from violations of academic integrity, bullying/hate crimes, drug dealing and the like. They don’t give a crap if you got a detention for arriving late, using a cell phone, drinking beer at prom, etc. Relax - the process is stressful enough.