You can do it with a custom function:
Function IsFormula(Target As Range) As Boolean
IsFormula = False
If Left(Target.FormulaR1C1, 1) = "=" Then IsFormula = True
Place this in a new code module (Alt+F11, Insert | Module, and Paste. Then Alt+Q to return to Excel.
To use the function, type =IsFormula(A1) -- you will get TRUE or FALSE. You can fill the formula down as required.
If instead, you just want to go to all cells containing formulas, try Edit | Go To | Special | Formulas