Hello,
Thank you for your question regarding moving your InMotion email to Office 365. You should download a backup of your email first, and save them to your local computer. You will need to do this with an email program. Then, add MX, TXT and CNAME records using the Advanced DNS editor in the cPanel. The settings can be found in your Office 365 account, here is a helpful MS guide on how to Create DNS records at any DNS hosting provider for Office 365.
Thank you,
John-Paul