withLatestFrom.ts

@Component({
  selector: 'my-component',
  template: '<div><input [formControl]="control"/></div>',
})
export class MyComponent implements OnInit {
  control = new FormControl('');

  ngOnInit() {
    fromEvent(document.body, 'click').pipe(
      withLatestFrom(this.control.valueChanges),
    ).subscribe(console.log);
  }
}