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?