Reporting Office 365 User Mailbox Connections

We have an Office 365 user who might have had his mailbox hacked. I need to run a report on just his mailbox showing the times that the mailbox was accessed/logged on to, and by what device (phone, tablet, laptop, or via Outlook/OWA). I've checked some of the available reports, like Get-MailboxActivityReport, Get-MailboxUsageReport etc. But these don't report mailbox connectivity or on a single mailbox, but across the organization.

What do I need to do, to get the reports I need?
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bjblackmoreAuthor Commented:

Thanks for the reply.

I saw these, via google, but don't think they offer the correct reports. The first link is to enable auditing, which would be after the fact now, and doesn't log client connectivity. The second is to audit mailbox access by non-owners, which won't report anything if the mailbox has been hacked, as the hacker would login as the user.
Vasil Michev (MVP)Commented:
Your best bet are the Azure AD reports. The sign-in reports will give you a quick overview, and the application usage ones more details. The later require Azure AD premium subscription however. Mailbox auditing will not help, you cannot audit owner events in EO.

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