How To Get Database Data When Changed in C# WinForms MongoDB

Question

How to retrieve data in C# winforms when only database has changed using MongoDB? I Coded Using Visual Studio. I've Form1 that Has TextBox and Button To Insert Data Into Database. Form2 Have Label that shown last data in database

What I've Tried :

MongoDB :
Database Name : test_chat
Exist Collection : table1

/* Code in Form1 */

public partial class Form1 : Form
{
    public static IMongoClient client;
    public static IMongoDatabase db;
    static String mongo_connStr = @"mongodb://127.0.0.1:27017";
    public Form1()
    {
        InitializeComponent();
    }

    public static void Connect()
    {
        try
        {
            if (client == null)
            {
                client = new MongoClient(mongo_connStr);
                db = client.GetDatabase("test_chat");
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        Form2 form2 = new Form2();
        form2.Show();

        Connect();
        if (db == null)
        {
            MessageBox.Show("Database Not Connected!", Application.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Error);
            return;
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        try
        {
            BsonDocument bDoc = new BsonDocument();
            bDoc.Add("Form1", textBox1.Text);
            var collection = db.GetCollection<BsonDocument>("table1");
            collection.InsertOneAsync(bDoc).Wait();
            textBox1.Text = String.Empty;
            textBox1.Focus();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
    }
}

/* Code in Form2 */
public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
    }

    private void Form2_Shown(object sender, EventArgs e)
    {
        Form1.Connect();
        CallMain();
    }

    public async Task CallMain()
    {
        Form1.Connect();
        var collection = Form1.db.GetCollection<BsonDocument>("table1");

        using (var cursor = await collection.Find(new BsonDocument()).ToCursorAsync())
        {
            while(await cursor.MoveNextAsync())
            foreach (BsonDocument doc in cursor.Current)
            {
                label1.Text = doc.GetElement(1).Value.ToString();
            }
        }
    }
}