how to put topic_id to the product table in Laravel

working with Laravel and I have both Topic and Product Tables. Product table contains relate to the Topic.

Topic.php

class Topic extends Model
{
    public function products()
      {
        return $this->hasMany('App\Product');
      }
}

Product.php

class Product extends Model
{
    public function Topic()
    {
        return $this->belongsTo('App\Topic');
    }
}

and I have the following controller store function in ProductController

public function store(Request $request)
    {
        $this->validate($request, array(
            'name'=> 'required|max:225',
            'menu'=> 'required|max:225',
            'slug' => 'required|max:225',
            'description'=> 'required|max:225',
        ));

        $product = new Product;

        $product->name = $request->name;
        $product->menu = $request->menu;
        $product->slug = $request->slug;
        $product->description = $request->description;
        $product->link = $request->link;
        $product->topic_id = $request->topic_id;
      
        $product->save();
    }

web.php

Route::resource('product','ProductController');

and Product/create.blade.php

<div class="card-body">
                  <form method="post" action="{{action('ProductController@store')}}" enctype="multipart/form-data">
                  {{csrf_field()}}
                    <div class="form-group">
                    <label for="exampleFormControlInput1">Product Name</label>
                    <input type="text" name="name" id="name" class="form-control" placeholder="Product Name">
                    </div>

                    <div class="form-group">
                    <label for="exampleFormControlInput1">Menu</label>
                    <input type="text" name="menu" id="menu" class="form-control" placeholder="Menu">
                    </div>

                    <div class="form-group">
                    <label for="exampleFormControlInput1">Slug</label>
                    <input type="text" name="slug" id="slug" class="form-control" placeholder="Slug">
                    </div>

                    <div class="form-group">
                    <label for="exampleFormControlInput1">Body</label>
                    <input type="text" name="description" id="description" class="form-control" placeholder="Body">
                    </div>

                    

                    <div class="form-group">
                    <label for="exampleFormControlInput1">Upload Product Image</label>
                    <input type="file" name="image" id="image" class="form-control" placeholder="Product Image">
                    </div>

                    <div class="form-group">
                    <label for="exampleFormControlInput1">Link</label>
                    <input type="text" name="link" id="link" class="form-control" placeholder="Link">
                    </div>
 <button type="submit" class="btn btn-success btn-lg btn-block" style="margin-top:10px">Create New Product</button>
                  </form>

Then I need to store topic_id in the Product Table. how could I pass topic_id to the ProductController store function?