To see if anyone has unauthorized access to your Google account, first log in, open your Gmail account, then click on the Profile image in the top right corner to select My Account . Now on the screen you will see your Google account page.
Next click on the Overview Account in the Personal info & privacy section.
The Account overview interface will now appear on the screen, click on View Dashboard (see overview page) then enter your Google account password to access the account overview page Google (Google Dashboard).
On the Dashboard will display all your active accounts. Here you tick the option Send me monthly reminders to check my account activity (send me a monthly reminder to check my account activity ) at the top of the Dashboard page.
Google will prompt you to visit the Dashboard monthly to check your account activity to find out if there is an unauthorized access to your account by strangers.
Good luck!