You can set up Excel to detect macros. Excel has a variety of security levels for macros so that you can choose the level that you are at ease with.
Very High All macros will be disabled even if they have valid digital certificates. This setting also disables all Component Object Model (COM) add-ins and smart tag recognizers, which you might need for Office programs to work as you expect.
High Unless you have a specific reason to do otherwise, High is probably the setting you should use. This is the default setting. Although macros from your trusted sources will run, you'll be prompted about unknown but signed macros, and unsigned macros will be disabled.
Medium Macros from trusted sources will run, but you'll be prompted about all unknown macros, including unsigned ones.
Low You should be very sure about using this setting. You will not receive any prompts or warnings. All macros will run.