Motion.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class Motion : MonoBehaviour {
    public GameObject target;
    public float speed = 5;

    void Update () {
        float deltaDistance = Time.deltaTime * speed;
        transform.position =
            Vector3.MoveTowards(transform.position,
                                target.transform.position,
                                deltaDistance);
    }
}