Accessing controls

out of any method, when I write string m = , after equal sign, TextBox1 is not in opened list.

Oh, you just don't get it. Your question is vague; you say you can't do something but that is all you say. Note that my reply was vague and it did not help you to understand the problem but that is the problem with vagueness. When saying things like "can't" and "doesn't" without clarification it is unlikely that you will get a useful answer without clarification. People that answer questions see many vague questions; it gets frustrating to have to ask for clarification so often. I have done it many thousands of times, and I am not exaggerating.

Myself tested it.

I tested It.
For example in class Form1, out of any method, I can't write something like this :

string m = TextBox1.Text;