- Open a browser, go to https://portal.office.com and sign into your account.
- Once signed in, click on your user account icon or picture at the top-right of the page.
- Click "View Account."
- On the "My Account" tab, click "Security info."
- Under Security info, review the authentication devices.
A password will be there and it will show when it was last changed. It may show your phone number. It will show your Authenticator app, which will show the time-based one time password along with the push notification. If you think a device does not belong there, but are not sure, please call the service desk. - Reviewing your devices - Click "Devices" from the "My Account" tab.
This will show you all active devices you've signed into. Review them - If any look suspicious, contact the service desk to go over them with a support technician. - Click "Recent activity" or "My sign-ins" from the My Account tab.
This will show you the most recent sign-ins for your account. It will show a general location, IP address, and other information such as the application or device type. If any sign-ins look suspicious, contact the service desk so a technician can help you evaluate these.

Check Office 365 Account for Suspicious Activity
Videos (Individual Steps Below):