Simpson, married to his childhood sweetheart for almost 19 years, had walked out on his wife and kids and into the arms of a younger woman. The breakup surprised his wife, his friends and even Simpson himself. Looking back, he says, it was a classic midlife crisis.
In that we have already provided the definitive answer to this question elsewhere (relying on rum extract), we assume your follow-up is seeking a non-alcoholic substitute for rum (as extracts can be as alcoholic as or more alcoholic than the spirits they replace).
Can you use brandy instead of rum in cake recipe. Almost certainly yes, but the flavors will be slightly different. Brandy is likely to be slightly more acidic than rum, but otherwise quite similar in composition, and should perform in the same way. If you want a more tailored answer, you should provide more information, such as the full recipe.