use-form-hook.js

import React from "react";
import { useForm } from "react-hook-form";

function SignUpComponent() {
  const { register, handleSubmit, errors } = useForm();
  const onSubmit = (data) => {
    // logs {firstName:"exampleFirstName", lastName:"exampleLastName"}
    console.log(data);
  };

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      <input name="firstName" ref={register} />
      <input name="lastName" ref={register({ required: true })} />
      {errors.lastName && <span>"Last name is a mandatory field."</span>}
      <input name="age" ref={register({ required: true })} />
      {errors.age && <span>"Please enter number for age."</span>}
      <input type="submit" />
    </form>
  );
}