What should i do to copy the selected word to the clipboard when i double-click

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Xml;
using MouseKeyboardActivityMonitor.WinApi;
using MouseKeyboardActivityMonitor;

namespace dictionar_demo_1
{
    public partial class MainForm : Form
    {
        private readonly KeyboardHookListener m_KeyboardHookManager;
        private readonly MouseHookListener m_MouseHookManager;

        public MainForm()
        {
            InitializeComponent();
            m_KeyboardHookManager = new KeyboardHookListener(new GlobalHooker());
           
            m_KeyboardHookManager.Enabled = true;

            m_MouseHookManager = new MouseHookListener(new GlobalHooker());
            m_MouseHookManager.Enabled = true;

            m_KeyboardHookManager.KeyPress += HookManager_KeyPress;            
        }


        private void HookManager_KeyPress(object sender, KeyPressEventArgs e)
        {
            string x = string.Format("{0}", e.KeyChar);
            if (x == "f")
            {
                m_MouseHookManager.MouseDoubleClick += HookManager_MouseDoubleClick;         
            }
        }


         private void HookManager_MouseDoubleClick(object sender, MouseEventArgs e)
           {
             Clipboard.Clear();
            
              // i want to copy the selected text 
              //from any document(like pdf, .html ,txt)
             // when i double-click a text
          
        }
    }//form
}