I'm afraid that the short answer is that you can't, well at least not directly. VBA and VBS are slight variant's and while you could save the code into a .vbs file I very much doubt that it would do anything without changing it to VB Script.
To make a .exe you will need something like Visual Studio. Even then you would probably need to rework your code to make it do it's job.
I guess it depends on what your code does.
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