Step 1: Open Settings
Step 2: Tap Mail, Contacts, Calendars
Step 3: Go to Add Account
Step 4: Select Exchange option
Step 5: Enter your office365 email account name in the Email field and the email account password in the Password field, then tap Next.
Step 6: Enter the following in the appropriate fields:
Username: Email Address
Step 7: Tap Done
Step 8: Choose the functionality you wish to sync, then tap Save.
Step 9: Your account will be configured and begin syncing.