How do I add user control dynamically and then get value from it

One strategy is to create an overloaded constructor for your 'Questions UserControl (but, do not delete the default Constructor !).

// in the UserControl
// assuming RichTextBox 'rtbQuestion holds the question text
// assuming RichTextBox 'rtbAnswer is where the user types an answer
// assuming Label 'lblQuestionId holds the integer Id

// the use of : this() here insures the default initializer is executed
// and any internal Controls are created
public Questions(Panel container, int id, string questiontext) : this()
{
    lblQuestionId.Text = id.ToString();
    rtbQuestion.Text = questiontext;
    container.Controls.Add(this);
    this.Dock = DockStyle.Top;
    this.BringToFront();
}

Be aware that some think it's a bad idea in WinForms to use overloaded Constructors with parameters: [^].

The above discussion, of course, does not cover how you access the user's response, since we don't know the how/where/what of that, yet.

If you want to go the more "standard route" of implementing Properties rather than creating an overloaded Constructor, and/or you need more run-time availability (set, get, values) of the internal state of your Controls in the UserControl:

Then, be sure you have exposed (by declaring them Public) Fields, Properties, Methods, you want a "consumer" of the UserControl (the Form, or ContainerControl, the UserControl is sited/hosted in) to have access to. For Example:

public string QuestionText
{
    set { rtbQuestion.Text = value; }
    get { return rtbQuestion.Text; }
}

// depending on your app design, you may not
// need a 'setter here ?
public string AnswerText
{
    get { return rtbAnswer.Text; }
}

public int QuestionId
{
    set { lblQuestionId.Text = value.ToString(); }
    get { return Convert.ToInt32(lblQuestionId.Text);}
}

There are other good reasons for using Properties, rather than Fields, to expose members of a Class to outside "consumers:" enforce encapsulation, etc.