Swing between two points

I have two positions. One is a stationary point. I have a line renderer that I draws a line between the two of them. I wan’t the second point to swing from the first point like its the end of a rope, without adding any hingeJoints. How would I be able to do this?

I’m making a grappling hook that sucks in the second point closer towards the first, and I want it to swing realistically.

Pendulum might offer some help here as it roughly approximates this motion.
simple pendulum

using UnityEngine;
public class SimplePendulum : MonoBehaviour
    [SerializeField][Range(0,90)] float _swingAngle = 33;
    [SerializeField][Min(0.001f)] float _length = 1.4f;
    [SerializeField][Min(0.001f)] float _gravity = 6f;
    [SerializeField] float _azimuth = 0;
    void Update ()
        float time = Time.time;
        float angle = -90f + ( _swingAngle*Mathf.Deg2Rad * Mathf.Cos( Mathf.Sqrt(_gravity/_length) * time ) ) * Mathf.Rad2Deg;
        // based on: https://gamedev.net/forums/topic/624653-how-to-code-a-swinging-movement/4938528/

        Vector3 p0 = transform.position;
        Vector3 p1 = p0 + Quaternion.Euler( 0 , _azimuth , angle ) * new Vector3{ x=_length };

        Debug.DrawLine( p0 , p1 , Color.yellow );