How to get Ember to detect a checkbox on change along with a glimmer tracked?

In ember js version 3.2.6, how do we get a checkbox to do extra logic on value changed?

Example, I have a checkbox (a toggle true/false) for updateServer. The existing code is using a glimmer @tracked and this work fine for showing some instant UI modification as can be seen on the application.hbs.

Value of update server:
 

But then I need to add some logic on value change, see onCheckboxChange. That function is called, but it seem the value of updateServer is not the one after click. It's the older one, before click. See picture.

How do I get the latest value of updateServer?

application.js

import Controller from '@ember/controller';
import { tracked } from '@glimmer/tracking';
import { action } from '@ember/object';

export default class ApplicationController extends Controller {
  @tracked updateServer = false;

  @action
  onCheckboxChange() {
    //some extra logic
    console.log(`at controller, updateServer is: ${this.updateServer}`);
  }
}

application.hbs

<label>
  <Input @type='checkbox' @checked= />
  Update Server</label>
<br />
Value of update server:

<br />