In addition to solution 1 by
CHill60[
^], you have to create Excel add-in which is executed together with MS Excel. So, macro will be avaliable whenever Excel is opened. You can create menu item for your macro (even option and checkbox).
In case, you want more details, don't hesitate to ask.
Assuming that you know how to create new Excel add-in, and you want to get more details about creating new menu item, please see:
VBA Express : Excel - Add custom menu items to the Menu Bar[
^]