System.Drawing.Graphics.FromHwnd drawing flickering

I'm drawing a circle as a second cursor in another application using System.Drawing.Graphics.FromHwnd(IntPtr). The shape draws properly beneath my cursor, but it flickers. I'm familiar with double buffering but this code is in an "Input" class I made, and not in a form. This is in a game so I'm pretty sure this is happening because the canvas in the game is being redrawn every frame and painting over my circle shape.

Is there a way to:

• Properly cause double buffering in this situation
• Eliminate flicker by some other means

Thank you

Using C# and .NET 5 if that matters (also since I know there will be inevitable comments on my class structure, this was quick and dirty to demonstrate the issue - I know that some of what I did here is not best practice).

public class Input
{
    private ThreadTimer timer;
    private IntPtr hwnd;
    private Graphics? winGraphics = default;

    public Input() 
    {
        timer = new ThreadTimer();
        timer.Interval = 15;
        timer.AutoReset = true;
        timer.Elapsed += Timer_Elapsed;
    }

    private void Timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
    {
        User32.POINT clientPt = new User32.POINT(Cursor.Position.X, Cursor.Position.Y);
        User32.ScreenToClient(hwnd, ref clientPt);

        var cursor = new Rectangle(clientPt, new Size(5, 5));
        winGraphics = Graphics.FromHwnd(hwnd);
        winGraphics.FillEllipse(new SolidBrush(Color.FromArgb(50, Color.Red)), new Rectangle(clientPt.X-15, clientPt.Y-15, 30, 30));
    }

    public void StartDrawMouse(IntPtr hwnd)
    {
        this.hwnd = hwnd;
        timer.Start();
    }

    public void StopDrawMouse()
    {
        this.hwnd = IntPtr.Zero;
        timer.Stop();
    }
}

ScreenToClient and its pinvoke data structure for POINT:

[DllImport("user32.dll")]
public static extern bool ScreenToClient(IntPtr hWnd, ref POINT lpPoint);

[StructLayout(LayoutKind.Sequential)]
public struct POINT
{
    public int X;
    public int Y;

    public POINT(int x, int y)
    {
        this.X = x;
        this.Y = y;
    }

    public static implicit operator System.Drawing.Point(POINT p)
    {
        return new System.Drawing.Point(p.X, p.Y);
    }

    public static implicit operator POINT(System.Drawing.Point p)
    {
        return new POINT(p.X, p.Y);
    }
}