I have not personally done this, but Microsoft has extensive documentation on their APIs available for their exchange services. Authentication will be the critical piece here and would likely be the hardest part of this integration.

In cloud, forms built using the new designer can integrate directly with Web APIs to query and retrieve this data and populate your forms.

In self hosted, you would have to query in workflow and load it into the form which could provide "stale" data. You theoretically could perform the API calls in JS from the form, but your IT admins would probably not appreciate storing credentials client side (unless you can sufficiently scope the credentials)