How to detect change events from datepicker within custom component?

I am trying to create a simple custom component for forms that contains both ngbDatepicker and Timepicker inputs.

How can I detect changes to those inputs? I’ve tried passing change events on the inputs like this:
<input class="form-control" placeholder="yyyy-mm-dd" name="dp" [(ngModel)]="date" ngbDatepicker #d="ngbDatepicker" (change)="onChange($event)">
and
<ngb-timepicker [(ngModel)]="time" (change)="onChange($event)" [meridian]="meridian"></ngb-timepicker>

I’ve also tried using
ngOnChanges(changes: SimpleChange){...}

But the change event is never detected.

Version of Angular, ng-bootstrap, and Bootstrap:

Angular: 4.1.2

ng-bootstrap: 4.1.2

Bootstrap: 4.1.2