If you want to migrate Exchange Server to Office 365 then you can try third-party software like
Shoviv Exchange Migration Tool. It allows smooth migration of multiple numbers of source mailboxes like EDB files, Outlook Stores, Office 365 mailboxes, Live Exchange mailboxes etc. into Live Exchange (On-premises), Office 365 and Outlook PST files. Along with this, Mailbox mapping option, Search Option, Filter Option and option to preview added source mailbox are also given. It is capable to smoothly migrate Live Exchange/Office 365 Public folders and Archive Folders into another Live Exchange or Office 365 Public and Archive Folders. The software is compatible with all the latest versions of Exchange and Windows.