SystemTimeWatcher

using System.Diagnostics;
using System.Threading.Tasks;
using Microsoft.Win32;

    public class SystemTimeWatcher : IDisposable
    {
        public delegate void SystemTimeChangedEventHandler(object sender, TimeChangedEventArgs e);
        public event SystemTimeChangedEventHandler SystemTimeChangedNotify;

        private bool SystemTimeChangedNotifyActive = false;
        Stopwatch sw = new Stopwatch();

        public SystemTimeWatcher() { }

        public bool InstallTimeChangedNotification()
        {
            if (SystemTimeChangedNotifyActive) return false;
            SystemTimeChangedNotifyActive = true;
            SystemEvents.TimeChanged += this.OnTimeChanged;
            return true;
        }

        private async void OnTimeChanged(object sender, EventArgs e)
        {
            if (sw.IsRunning) return;
            sw.Start();
            var args = new TimeChangedEventArgs();
            OnSystemTimeChangedNotify(args);
            await Task.Delay(200).ConfigureAwait(false);
            sw.Stop();
        }

        protected virtual void OnSystemTimeChangedNotify(TimeChangedEventArgs e)
            => SystemTimeChangedNotify?.Invoke("System Time Changed", e);

        public class TimeChangedEventArgs : EventArgs
        {
            public DateTime CurrentTime { get; set; } = DateTime.Now;
            public int SomeOtherUsefulValue { get; set; }
        }

        public void Dispose() => SystemEvents.TimeChanged -= this.OnTimeChanged;
    }