If you want to include both simpler than what I saw here, you can do it just by including your button inside form.
Example with a function sending a message:
<form>
<mat-form-field> <!-- In my case I'm using material design -->
<input matInput #message maxlength="256" placeholder="Message">
</mat-form-field>
<button (click)="addMessage(message.value)">Send message
</button>
</form>
You can choose between clicking on the button or pressing enter key.