Usage patterns
〈事〉はもちろん、〈事〉もnot only ... but also ... (used to add extra information)
He can speak not only English but also French.
もちろんですused alone as a polite affirmative reply meaning 'of course'
"Could you help me?" "Of course."
〈事〉はもちろんのことneedless to say ...; not to mention ...
Not to mention studying, exercise is also important.