Q: My phone was hacked before the new update...

Hello, I recently found things online that were in my Phone that I know not a single person could have and they had been posted by a fake account onto a lot of websites. I am 100% sure that my phone had been hacked, however if it were from the company that was caught a few days ago and I updated it after the fact of my phone being hacked into, would that mean they cannot access my phone anymore? Or is rhere a step I need to take