class MyForm extends React.Component {
      formState = new ReduxHookForm();

      render() {
        const { register, handleSubmit } = this.formState;
        return (
          <form onSubmit={handleSubmit(this.handleSubmit)}>
            <input name="firstName" ref={register} />
            <select name="gender" ref={register}>
              <option value="male">male</option>
              <option value="female">female</option>
            </select>
            <input type="submit" />
          </form>
        );
      }

      handleSubmit(data) {
        console.log(data);
      }
    }