I can't tell if it's a serious comment or not but in case it's serious: Why even buy a laptop? If you're paranoid enough to want to do this sort of thing to something you're paying over $1.5k for, have you realized the consequences of what other things a bad agent can do?

Your data, your files are more valuable to the NSA than your microphone. If they care about what you're saying, your house is already bugged.