Make a measure, and instead of evaluating arithmetic, evaluate a string:
// All below are measures in my model
"This measure returns text"
This Measure returns text based on a field value! =
VALUES( 'Sample'[SomeField] )
,1, "That's a one"
,2, "Well that looks like a 2"
,3, "By golly, thats a seventeen!"
My 'Sample' is just a 3-row table with values of [SomeField] = 1, 2, 3.
You can see that my matrix uses [SomeField] as the row labels. My measures are both in the Values area. Each returns text.
I'm happy to help more, but I don't know what sort of detail you're looking for.