Check out example codes for "imagetarget found event vuforia c#". It will help you in understanding the concepts better.

Code Example 1

private bool isTrackingMarker(string imageTargetName)
    {
        var imageTarget = GameObject.Find(imageTargetName);
        var trackable = imageTarget.GetComponent<TrackableBehaviour>();
        var status = trackable.CurrentStatus;
        return status == TrackableBehaviour.Status.TRACKED;
    }

Learn ReactJs, React Native from akashmittal.com