Get only related items in Laravel

on my Model
Models/Book.php
I coded this relation

public function getBook() { return $this->hasOne(BookCover::class, 'book_id', 'id'); }

on my Controller

public function getBookCover() { $bookCover = Book::with('getBook')->get(); return response()->json( $bookCover );

It will return

{ "id": 1, "uuid": "89833855-5777-4baf-9218-2c715619dd9b", "created_at": "2023-01-10T08:00:00.000000Z", "updated_at": "2023-01-10T08:00:00.000000Z", "get_book": { "id": 1, "uuid": "32eb81d7-d36d-4333-ba59-f40a3809dc71", "created_at": "2023-01-10T08:00:00.000000Z", "updated_at": "2023-01-10T08:00:00.000000Z", "book_name": "في أعماق الصمت", "book_image": "https://www.noor-book.com/publice/covers_cache_webp/2/5/d/6/6d212d49275d67ffe387771061a711fa.jpg.webp", "book_rate": 5, "book_page_number": 210, "book_description": "رواية فلسفية تستكشف معنى الوجود والصمت الداخلي في عالم مليء بالضجيج، تأخذ القارئ في رحلة روحية عميقة.", "book_id": 1, "views": "0", "category_id": 5 }

I want to get only "get_book" only