Did the user open the document before approving it? How to log this in workflow logs?

Hi there,

My workflow on Document Library needs to keep logs of:
- When a user is assigned the document for approval/rejection, did he actually open it or download it before approving?

How to get this information please in workflow logs please? (I know this information exists in SharePoint Audit logs but that does not work for me - I need this in workflow logs).

Thanks.