Jumping to add force but stop after a while

Hello I’m Leonardo, english is not my native language and I’m new to coding so i hope you will understand.

I’m trying to make my character jump when I hold the button and add a negative force on the y axis when i release.

I tried saying this:

if (Input.GetButton) { //if you hold the button

    rigidbody2D.AddForce (new Vector2 (0, jumpForce));

}

if (Input.GetButtonUp) {

    rigidbody2D.AddForce (new Vector2 (0, -jumpForce));

}

But the result was that the character goes up as long as i hold the button, but i want
it to go up and after 1 second (or less) to go down even if i hold the button for an infinite amount of time.

So my question is:

Can I add a force and after a while stop adding it? If not, what else can
I do to have the same effect?

Thanks in advance!

oh and forgot to say c# only

When I wrote the code it gave me an error in “ForceMode.Impulse”, but now I figured out I had to write “ForceMode2D.Impulse” and it works perfectly. Thanks! :]