Does Knock Off get the boost if the opponent is holding a Mega Stone?

Question

Knock Off gets a buff when it hits a Pokemon with an item. If you hit a Pokemon with a Mega Stone, does it get the boost even though the Stone is not knocked off?

Answer 1

No, it does not get a boost if it's holding a mega stone.

>Knock Off's power has been increased from 20 to 65, and its PP increased from 20 to 25. In addition, it will deal 50% more damage if used on a Pokémon holding an item other than a Mega Stone or a Giratina holding a Griseous Orb. Sticky Hold does not prevent this bonus.

Source: Bulbapedia

Hope I helped.

Answer 2

Knock Off does 50% more damage against a target with an item (other
than a MegaStone).

Nope
Source