How to set text at insertion point in input

[Cypher18]

Hello,
I tried to set text at insertion point in input. That is my code!

– HTML –

<button ion-button full (click)="clickBtn()"> ABC </button>

<ion-item>

<ion-label fixed> Username </ion-label>

<ion-input type="text" [(ngModal)]="userName"></ion-input>

</ion-item>

– TS –

userName: any;

clickBtn(){
   this.userName += "ABC";
}

– Image –

– Please Help –