If there is no police report, nothing noted on your driving record
and you paid out of pocket for any damages you caused, it would be
unlikely that your insurer would know about a minor accident you were
in. That's also true if you were in an unreported single-car accident
that resulted in no claims.
If there are claims involved, your car insurance company will know
about the accident even if you don’t get a police report or personally
notify your insurer of the incident. When claims are paid out, auto
insurance providers place the claims information into a central
database.
When you apply for a new policy with a new insurer, it, too, will
obtain your claims history, and see any previous accidents and claims
you had.