It's called an "airborne throw" ... a player can catch the ball in mid-air, and then play the ball before landing on the court.
Also, an opposing player cannot move into the natural landing area of an airborne player once the airborne player has left the floor.
But that would work both ways ... once a defender had jumped to intercept the path of the ball, an attacker could not jump to attempt an airborne throw.
The reasons why the move is not used in practice are ...
1. Netball players tend to be about 2 ft shorter than basketball players.
2. A netball hoop doesn't have a back board, so greater shooting accuracy is needed ... if you overshoot, the ball doesn't come back for a second go at the hoop. This makes it extremely hard to shoot whilst moving.
3. In view of 2. above, a player who tried to shoot in mid air too much would keep putting the ball out of the court, and giving away possession. This would lead to regular towel thwackings from her teammates in the changing room.
4. A netball hoop is on a stand, not fixed to the wall. If you grab it (slam dunk style), it will topple over.