Time.deltatime not working.

I am trying to change players y velocity using deltatime. but when I press the jump key it doesn’t jump. The jump key is assigned to a key.

if((Input.GetKeyDown(jump)) && (isAirBorn == false)) {
float time = Time.deltaTime * 10;
vertVel = time;

@Namey5 I am going to make it so jump fades in and out fast and middle of jump is slower, while jump only lasts 0.7 - 0.8 seconds. But im trying to get the character off the ground first.