Invalidate one section with OnMouseMove

How can I Invalidate just one section? I should only draw mål.Rita once. And then redraw sikte.Rita with onmousemove(). Thanks for help

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Måltavla
{
    public partial class Form1 : Form
    {
        Måltavla mål;
        Sikte sikte;
        
        public Form1()
        {
            InitializeComponent();
            mål = new Måltavla(ClientSize.Width / 2, ClientSize.Height / 2, 200);
            sikte = new Sikte(ClientSize.Width / 2, ClientSize.Height / 2, 50);
        }
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            mål.Rita(e.Graphics);
            sikte.Rita(e.Graphics);
        }

        protected override void onmousemove(MouseEventArgs e)
        {
            base.onmousemove(e);
            sikte.X = e.X;
            sikte.Y = e.Y;
            Invalidate(); //
        }
    }
}