Triying to make a character take knockback in a parabolic motion in 2D.

I'm trying to make a character do a parabolic motion when taking damage but it's not working out. This is the line of code I have for the movement:

     theRB.AddForce(new Vector3(m_jumpX, m_jumpY, transform.position.z), ForceMode2D.Impulse);

Instead of moving in an arc my character is doing the same motion this guy was getting in this reddit thread: https://www.reddit.com/r/Unity2D/comments/57hv0u/unity_2d_knockback/