cloudHQ can be used to migrate all or just selected Dropbox accounts to Office 365.

Single user migration:

If you are looking to migrate just one Dropbox account (either personal or Dropbox business account), then you just need to create a sync pair from that Dropbox account to Office 365 OneDrive account or to Office 365 SharePoint Library.
The instructions how to migrate a single Dropbox account to Office 365 OneDrive are here
The instructions how to migrate a single Dropbox account to Office 365 SharePoint Library are here

Note that sharing metadata will be migrated only and only if:

Multiple user migration:

If you are an admin of Dropbox for Business domain then cloudHQ can:

  1. migrate all your Dropbox accounts to corresponding Office 365 OneDrive accounts. All sharing metadata will be migrated too.
  2. migrate all Dropbox Team folders to corresponding Office 365 SharePoint Document Libraries.

The instructions how to migrate a multiple Dropbox for Business accounts to Office365 OneDrive Business accounts are here