useState to update multiple values in React

You should add name attributes to input tags. Each name must refer to key in AllValues object.

const [allValues, setAllValues] = useState({
   mobile: '',
   username: '',
   email: '',
   password: '',
   confirmPassword: ''
});
const changeHandler = e => {
   setAllValues({...allValues, [e.target.name]: e.target.value})
}
return (
   <input type="text"
       className="form-control"
       id="mobile"
       name="mobile"
       placeholder="Enter a valid mobile number"
       onChange={changeHandler}
   />
   // ...
)