Use a calculated field similar to the following:

IF MIN([Hierarchy Level 3]) = MAX([Hierarchy Level 3]) 
THEN [Measure 3] 
ELSEIF MIN([Hierarchy Level 2]) = MAX([Hierarchy Level 2]) 
THEN [Measure 2] ELSE [Measure 1] 
END

On the workbook, there is the example "Display Result With Description"

IF MIN([Item]) = MAX([Item]) THEN "Displaying Item SALES: " + STR(ROUND(SUM(Sales),2)) //This will display the text and sum of Sales for the item - It is also rounding the result to show 2 decimal digits.
ELSEIF MIN([Category]) = MAX([Category]) THEN "Displaying Category PROFIT: " + STR(ROUND(SUM(Profit),2)) //This will display the text and sum of Profit for the Category
ELSEIF MIN([Department]) = MAX([Department]) THEN "Displaying Department PROFIT: " + STR(ROUND(SUM(Profit),2)) //This will display the text and sum of Profit for the Department
END