1. Select the Calendar app from the google application selection menu.
2. Click on the gear icon and select settings.
3. From the calendar tab select export calendar, this will download a ical zip file, make sure to extract this file.
4. Extract the zip file.
5. Login to office365 (https://portal.office.com) using your email and password and select calendar app from the dashboard.
6. Now from the menu above select Add calendar and select from file option, this will ask for ICS file.
7. Upload the extracted ICS file downloaded from google and click save.