Programming a macro in excel to generate a random number between a, b

I am building a spreadsheet in excel, the spreadsheet functions as a data keeping table that updates different values as it needs to, one of the values that I'm interested in streamlining is essentially a random number generator. I already have knowledge of the simple RANDBETWEEN() function inside the cells of excel. however this only returns one (1) value, I would like to be able to assign this to a function to get it return a different value every time the button is hit. I can create the button, I have the cell.. I'm not sure exactly why I cannot link the two? Ive tried looking through already asked questions of this but not found anything super close to my problem (though I realize for someone who is adept with excel this might be a trivial problem.) I however am not adept at excel, and am still learning all the inner workings and things I can do with excel.

Long story short, can someone help me get a button that every time it is clicked a cell (lets say cell a1) gets a different value between values a, to b.

again sorry if this is trivial, ive tried all I can to do this on my own and I'm just not having any luck.