As you may know, Microsoft is providing a cloud based service to monitor your infrastructure called Operation Management Suite (OMS) which can work as a standalone solution (even if it is not yet at the same level than SCOM) or integrated with SCOM.
Now, you can also monitor your Office 365 tenant with OMS.
When you connect to your OMS portal, you should see an Office 365 component
If not, go to Settings\Connected Sources
Click Connect to connect to your Office 365 with your Office 365 administrator account
Once authenticated, you need to grant the required permissions
When you got this confirmation pop-up, you are all done
The data will start being gathered – NOTE it may take up to 4 hours
Once the data have been gathered, you get an insight
When clicking on the Office 365 dashboard, you can see all activities performed and by which account and then for each workload (Exchange, SharePoint or Azure AD) you get more details