Code Signing

One way to prevent users from accidentally changing your macro project and invalidating your signature is to lock the macro project before applying the signature.
Even if you have locked your macro project, another user may still be able to replace your signature with another signature.
Corporate administrators can also re-sign templates and add-ins to ensure that only approved content is run on company computers.

link - support.microsoft.com/en-gb/office/digitally-sign-your-vba-macro-project-956e9cc8-bbf6-4365-8bfa-98505ecd1c01 

Apply a Signature to a VBA Project

Tools, Digital Signature
You will now have the option to choose a certificate to use as a code signing certificate for this project.
All valid certificates installed to your machine with code signing enabled will be displayed to you.
Choose the appropriate certificate from this list, then choose OK twice to apply this certificate to the project.

Macro Security Settings

Digital Signatures

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