How to handle form input with checkboxes correctly? I have a form definition:

this.cargoSignupForm = new FormGroup({
        trucksToSelect: this.fb.array([])
      });

Submit function:

onSignupForCargo(cargoId: string) {
    this.cargosService.signupForCargo(
      cargoId,
      this.cargoSignupForm.value.trucksToSelect
    )
  }

and template:

<form [formGroup]="cargoSignupForm" (submit)="onSignupForCargo(cargo.id)" *ngIf="!isLoading">
                                      <div *ngFor="let truck of (trucksByCargoId.get(cargo.id)); let i = index">
                                        <mat-checkbox formControlName={{truck._id}} value={{truck._id}}>{{truck.regNumber}}</mat-checkbox>
                                      </div>
                                      <input type="submit" value="GO" class="button-basic">
                                    </form>

I want to export array of selected checkboxes(value must be truckId) to backend. Thank you for your time!