<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"
          xmlns:local="clr-namespace:WpfApp1"
          mc:Ignorable="d"
          Title="MainWindow" Height="450" Width="800">
     <StackPanel HorizontalAlignment="Stretch">

          <Button Command="{Binding CommandClickMyButton1}"
               x:Name="MyButton1"
               Content="Hello"
               Margin="0 100 0 0"
               HorizontalAlignment="Center"/>
         
     </StackPanel>
</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 CommandClickMyButton1 => new ClickCommand(ClickMyButton1);

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

          public void ClickMyButton1(object parameter)
          {
               Point mousePosition = Mouse.GetPosition(MyButton1);
               Point mousePositionScreen = MyButton1.PointToScreen(mousePosition);
               Point mousePosition2 = MyButton1.PointFromScreen(mousePositionScreen);
          }
     }
}