Email and Calendar
You can look up someone from the other campus in the To/Invitee field as you normally would for your own campus:
OneDrive
Sharing a OneDrive file or folder to someone from the other campus is done the same way as sharing to someone on your own campus:
SharePoint
To share a SharePoint site:
From the Sharepoint site, click the Gear menu icon, then select Site Permissions.
From Site Permissions, select Add members > Share site only.
Enter the employee’s name or email address: