C# Use textbox value in another cs file : I'd like to add a WinForm into my Console App:

    namespace ExchangeNativeDemo.Window
    {
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }


        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }
    }
    }

I would like to pass textbox1 value to Program.cs, like:

    var emailaddress = textbox1.value

In program.cs:
    
    using ExchangeNativeDemo.Window;

    namespace ExchangeNativeDemo
        class Program
    {
        static void Main(string[] args)
        {

But I got the error: "is inaccessible due to its protection level".

What I missed?

Thanks! 