<Window x:Class="WpfApp1.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"
          mc:Ignorable="d"
          Title="MainWindow" Height="450" Width="800">

     <Grid Background="LightGray">
          <Grid.InputBindings>
               <MouseBinding Gesture="LeftDoubleClick" CommandParameter="{Binding}" Command="{Binding MyMouseLeftDoubleCommand}"/>
          </Grid.InputBindings>
     </Grid>
    
</Window>

using System.Windows;
using System.Windows.Input;

namespace WpfApp1
{
     class ClickCommand : ICommand
     {
          public event EventHandler CanExecuteChanged;
          private Action<object> _callback;
          public ClickCommand(Action<object> callback)
          {
               _callback = callback;
          }

          public virtual void Execute(object parameter) { _callback(parameter); }
          public virtual bool CanExecute(object parameter) { return true; }
     }

     public partial class MainWindow : Window
     {
          public ICommand MyMouseLeftDoubleCommand => new ClickCommand(MyMouseLeftDouble);

          public MainWindow()
          {
               InitializeComponent();
              
               // for binding
               this.DataContext = this;
          }

          public void MyMouseLeftDouble(object parameter)
          {
               MessageBox.Show("thank you for mouse double click!");
          }
     }
}