One option is to use an Excel compiler, which is a third-party application that turns your Excel file into a .exe file. The user still has to have Excel installed to use it, but they will not have access to formulas or VBA.
I have not used one so I can't make a recommendation. But just as one example of what I'm talking about, look up DoneEx.
These are much more secure than the built-in Excel protections, but of course nothing is absolutely secure against a motivated attacker. I would think you would have to have a very high level of expertise to crack one of these.