Managing personal Outlook.com account settings, security, and privacy
Hi there! I'm Ben a fellow member here in the community.
Sorry to hear about what happened on your account and I know how important it is for you to recover it!
For hacked account issues, it is really best to submit a report about it. There is a form you can fill out that will go to a team specially equipped to handle scenarios like this.
Please fill out this form https://aka.ms/recovermyaccount you should get an email response within 4 hours the latest.
The team on the other end will help work through the issue with you.
Note: The form is hosted on the Xbox support site but is available to all Microsoft account holders not just those who use Xbox.