An integrated threat protection solution designed to detect, investigate, and respond to cyber threats across Microsoft 365 services.
Hello Fred,
Its really alarming when you notice that someone maybe accessing your computer however I suggest to isolate the device itself, consider changing your computer password right away and check the recovery email for the password or account. Once the computer is stable run the Windows Security go to start menu, type in Windows Security into the search bar then select it to open. From there you do a deeper inspection by selecting Scan options which will allow you to run a Full scan or Offline scan.
Installing an antivirus and firewall software to keep the computer safe from any possible unauthorize access.
I hope this answer is helpful if you have further questions feel free to reply back
Regards,
Marcelo