c# Windows API get value from caption field

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Windows

.NET

API

request

c# VS.

When I use WinSpy++ on windows calculators result field, it shows the result in a field called Caption.
Is it possible to copy the Caption field from the calculator into a messagebox on my app ?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {

    [DllImport("user32.dll")]
    public static extern int SendMessage(int hWnd, uint Msg, int wParam, int lParam);

    [DllImport("user32.dll")]
    static extern int FindWindow(string lpClassName, string lpWindowName);



        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            const int WM_COMMAND = 0x0111;

            int thisWindow = FindWindow("CalcFrame", "Calculator");

            //This writes the number 8 in calculator
            SendMessage(thisWindow, WM_COMMAND, 0x08A, 0);

        }




    }
}