How to send a header to a MERN api - mern

Question

I am creating a MERN application and I have a problem, in the back end I have the protected routes through a function called verifytoken that looks for the token as a header, on the other hand, in the front I receive a token that I keep in the local storage, how can I send the local storage as a header when calling that API?
I attach my code
frontend function that receives the token and stores it in localstorage
`import axios from "axios";
const jwtString = 'jwtlibraryyt'
export const loginUser = async (userObj) => {
const response = await axios.post(`http://localhost:3001/login`, userObj);
const { user, token} = response.data;
const {_id, ...userStored} = user;
localStorage.setItem(jwtString, token );
return response;
}`
frontend function that tries to call the protected route and send the local storage as a header
`const Books=()=> {
const [books, setBooks] = useState([]);
useEffect(() => {
getBooks();
},[])
async function getBooks(){
if(!localStorage.getItem("jwtlibraryyt")){
}
else{
const response = await axios.get('http://localhost:3001/books',{ headers: { token:localStorage.getItem('jwtlibraryyt') }});
setBooks(response.data);
}
}`
protected backend path
`router.get('/books', UserController.verifyToken,BookController.allBooks)`
verifytoken function found in the backend
`UserMethods.verifyToken = async (req, res, next) => {
let token = req.headers["token"];
if (!token) return res.status(403).json({ message: "Dame un token" });
try {
const decoded = jwt.verify(token, SECRET='elbicho');
req.currentUserId = decoded._id;
const user = await Users.findById(req.currentUserId, { password: 0 });
if (!user) return res.status(404).json({ message: "No se encontro el usuario" });
next();
} catch (error) {
return res.status(401).json({ message: "Usted no tiene autorizacion" });
}
};`