I do not think this would be possible with the caption of the form. But you could use the format string widget from the appstore to use this on the top of your form. Then with styling you could come close.
Regards,
Ronald
Alternatively, you can make rows conditionally visible based on the enumeration value and use different captions for each visible row. It's not a very maintainable solution, but in isolated cases it's the easiest work around.