You can find out the latest version of the Office 365 Add-In by navigating to the "Details and Support" section in the App Listing on Microsoft AppSource. Here is a direct link to this section with the latest version number. This version number will update over time as HubSpot releases new versions of the Office 365 Add-In.
To find out the latest version of the Outlook Add-In, you navigate to the Outlook App Store (Add-Ins listing) and view information about the add-in such as the version information and add-in developer. This external help article from Microsoft explains how to view access your Add-Ins and view more information on each add-in.