Could I cover the mouth of the wizard I grappled to silence them?
I am a player in a Curse of Strahd (5e) campaign. I am playing a monk and leaning towards grappling enemies in combat. I was thinking (haven't attempted yet): shouldn't I just be able to silence a grappled enemy by covering their mouth? To me, it would make sense to be able to do so since, lore-wise, most spells have a verbal component that needs to be said out loud.
Would it make sense to be able to do so? Maybe have the enemy roll a STR/DEX save? Or would it break the combat/be too over-powered?
EDIT: I do understand that it is not RAW, but I was thinking if and how it could be made to work without breaking the game. Also, I wasn't intending grapple itself to silence the caster; I rather intended grapple + additional action to "gag" the character and possibly having to use an action/bonus action every turn + concentration to keep/refresh the gag, and saving throw for enemy every turn. The idea would essentially be to take one enemy out of the fight while I am also essentially taken out of the fight.
EDIT2: The intention here is primarily for role-playing (being able to neutralize a spellcaster without harming them) rather than creating an unbalanced game-breaking mechanic. In hindsight, I probably should have titled the post as "how can I make this work?" rather than "would this work?".
EDIT3: I agree that it makes a lot more sense to be able to try to gag the opponent if I am restraining them, rather than just grappling.