Are you sure that you don't mean workbook and not worksheet?
Both of the first two answerers gave you some good data, it's just that neither one really pieced things all together.
1.) Only the really old Excel macros that didn't even run on VBA are actually contained on sheets. If they are the really old macros, there's not really much you can do.
2.) If you are wanting to hide just a worksheet, there are really two or three ways you can do it. Here are the easiest two ways:
a. Select your worksheet then go to Format > Sheet > Hide
b. Press Alt + F11 to open the Visual Basic Explorer window, then in the Project Window in the top left corner click on the worksheet in the workbook you want to hide. Then go down to the Properties window to the Visible property. Set that to xlSheetHidden or xlSheetVeryHidden. The difference between the two is that the one hides the worksheet but if you go to Format > Sheet > Unhide you will see any sheets that have xlSheetHidden. Ones that are set to xlSheetVeryHidden aren't listed and can't be unhidden by the user without going through Visual Basic somehow. If you can't view the Project or Properties Windows go to View > Project Explorer for the Project window or View > Properties Window for the Properties Window.
3.) Before you consider using an Add-In, you might consider using the PERSONAL.XLS file. The PERSONAL.XLS file works just like an Add-In. The PERSONAL.XLS file opens as a hidden file everytime you open Excel as long as the file has been created. If it has been created, you should see a project called PERSONAL.XLS in the Project window. To create the PERSONAL.XLS file, just record a macro and change "Store Macro In" from "This Workbook" to "Personal Macro Workbook" when you record it. Then just put your macros in the PERSONAL.XLS file.
4.) Another way of doing pretty much the same thing as the PERSONAL.XLS file is to do an Add-In. Follow the one answer's instructions on that. No need for me to put the instructions here and make my answer longer than it already is.