Follow these steps to migrate Exchange On premises to Office 365
Go to Office 365 in EAC
Click Add and choose to Migrate to Exchange Online under Recipients>Migration.
On the, select a migration type page, select Remote move migration, then click next. It will take you to Select the Users page.
Then click Add. Here you get the option to select on-premises Exchange users in case you want to migrate to Office 365. Then you have to click Add, then Ok, then Next.
Then put the credentials of the on-premises administrator. Enter the Windows user account credential page.
Make sure that your on-premises Exchange Server (FDQN) is there on the “Confirm the Migration” endpoint page. Then, click next.
In the Move configuration page, create a migration batch. You can do this by providing the required details. Then, click Next at the end.
Finally, at the Start the batch page, choose one recipient to receive the report. After batch completion, check the automatically complete the migration batch Box. Click New. Know more about Office 365 Cloud migration in detail.
I hope this method will be helpful!