Bạn tham khảo Code bên dưới thử nha:
Code XAML

<Window x:Class="EventAppWPF.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:EventAppWPF"
        mc:Ignorable="d"
        Title="MainWindow" Height="200" Width="470">
    <Grid>
        <TextBox Text="{Binding MyName,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>
    </Grid>
</Window>

Code CS

using System;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;

namespace EventAppWPF
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private String _myName;
        public String MyName
        {
            get { return _myName; }
            set { _myName = value; OnPropertyChanged(); }
        }


        public MainWindow()
        {
            InitializeComponent();
            DataContext = this;
        }

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged([CallerMemberName] string nameProp = null) => PropertyChanged(this, new PropertyChangedEventArgs(nameProp));
    }
}