If myCustomDirective has an output @Output() someEvent:EventEmitter = new EventEmitter(); then you can use
<div myCustomDirective (someEvent)="callSomethingOnParent($event)">HELLO</div>
If myCustomDirective has an output @Output() someEvent:EventEmitter = new EventEmitter(); then you can use
<div myCustomDirective (someEvent)="callSomethingOnParent($event)">HELLO</div>