How to fire parent function on change when something happens in child without touching the child component

Question

So I have this child component which I wish I don't want to disturb, this component has a <ng-select> in it. I want the the parent component to detect if there is any changes made to this child component. So it looks like this now:

Parent-component.html

<div>
 <child-component></child-component>
</div>

I have a function in the ts file if there is a change happening like this:

Parent-component.ts

changeFunction() {
 ***something happens***
}

I initially just tried adding a (change)=changeFunction() to the child component, making it like this:

<div>
 <child-component (change)=changeFunction()></child-component>
</div>

but that doesn't seem to work.

Is there anything I could do to detect when a change is made in the child component without having to do anything on the child component itself?