Upload image with object

Question

I am using @iplab/ngx-file-upload for drag-drop images in my project, i have object which i am sending to server, but how can i append my images to it?

.ts

  private filesControl = new FormControl(null);
    this.createEstimation = this.fb.group({
      clientType: ["0", Validators.required],
      privateNumber: ['', [Validators.required, Validators.pattern('[0-9]+'), Validators.minLength(11), Validators.maxLength(11)]],
      firstName: [''],
   files: this.filesControl)};

send() {
  let value = this.createEstimation.value;
      this.finalData = {
        client: {
          clientType: parseInt(value.clientType),
          privateNumber: value.privateNumber,
          firstName: value.firstName.split(' ').slice(0, -1).join(' '),
          lastName: value.firstName.split(' ').slice(-1).join(' '),
        }
};
      const formData = new FormData();
      formData.append('images', value.files);
      this.service.createEstimation(this.finalData).subscribe(
        (res: any) => {
          console.log(res);
        },
        err => {
          console.log(err);

        }
      );
}

.html

<file-upload formControlName="files"></file-upload>

.service

  public createEstimation(formData) {
    return this.http.post(this.API_SERVER + '/url', formData);
  }