Final answer:
The best solution is to migrate to Microsoft 365.
Step-by-step explanation:
The best solution to minimize the CapEx impact while updating your systems in this scenario would be to migrate to Microsoft 365.
Migrating to Microsoft 365 will allow you to upgrade both Microsoft Exchange Server and Microsoft Office to their latest versions without making a significant upfront investment in hardware or software licenses.
By moving to a cloud-based solution like Microsoft 365, you can also benefit from automatic updates, enhanced security features, and the flexibility to access your system and files from anywhere.