A family of Microsoft word processing software products for creating web, email, and print documents.
VBA does not have a RegExp function.
If you are used to using one, it may be on Windows Word, where you can reference the Microsoft VBScript Regular Expressions library and use its RegExp. But that library does not exist on Mac, so you either have to
a. find a Mac equivalent (probably shell out and use a command line utility - I have never tried that for regex) or
b. limit yourself to one of the things available in Word. I think that's either the simple wildcard stuff you get with the VBA Like keyword, or the wilcard pattern matching you get with Word's Find object (which is like regex, but nothing like as powerful as a typical modern regex implementation).