spawn and drag game object without leaving mouse button

I made some code for this. It is not very elegant or pretty, it could use a lot of optimization... but it does work.

First, make a new layer called "SpawnedObject".
Second, add this script to any object in the game.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class SpawnAndDrag : MonoBehaviour
 {
     // Drag the prefab you would like spawned into this variable
     //  in the Unity inspector
     [SerializeField]
     GameObject objectToSpawn;
 
     // Reference to the instantiated object
     GameObject spawnedObject;
 
     // Stores the information of where our raycast hits
     RaycastHit hit;
 
     // The ray we're going to cast with our left click
     Ray ray;
 
     // The layer number for the "SpawnedObject" layer and 
     //  a layer mask that will tell the ray to ignore that layer.
     int spawnedObjectLayer, spawnedObjectMask;
 
     // Use this for initialization
     void Start()
     {
         // Get the number for the "SpawnedObject" layer.
         spawnedObjectLayer = LayerMask.NameToLayer("SpawnedObject");
 
         // Create a layer mask that ignores this layer
         spawnedObjectMask = ~(1 << spawnedObjectLayer);
     }
 
     // Update is called once per frame
     void Update()
     {
         // Create a ray so we can raycast it later
         ray = Camera.main.ScreenPointToRay(new Vector3(Input.mousePosition.x, Input.mousePosition.y, 10f));
 
         // If we click/hold the left mouse
         if(Input.GetMouseButton(0))
         {
             // Raycast from our Camera to our mouse position
             // If the ray hits an object that does not have a layer of "SpawnedObject"
             if (Physics.Raycast(ray, out hit, 999999f, spawnedObjectMask))
             {
                 // If we don't have a spawnedObject yet.
                 if (spawnedObject == null)
                 {
                     // Spawn our object at the mouse's position
                     spawnedObject = Instantiate(objectToSpawn, hit.point, Quaternion.identity);
 
                     // Set it's layer to "SpawnedObject" so that our raycast ignores it
                     spawnedObject.layer = spawnedObjectLayer;
                 }
                 // If we do have a spawnedObject
                 else
                 {
                     // Changes the position of our spawned object to
                     //  where the mouse's position is.
                     spawnedObject.transform.position = hit.point;
                 }
             }
         }
         // If we let go of the left mouse button
         else if (Input.GetMouseButtonUp(0))
         {
             // Sets the object's layer back to "Default"
             spawnedObject.layer = 0;
 
             // Gets rid of our reference for the spawned object so
             //  that we can't drag it anymore.
             spawnedObject = null;
         }
     }
 }
 

Third, click on the object you put the script on and drag the prefab of the object you want to spawn into the slot called "Object To Spawn" on the script.