public class CustomTextAnnotation : RectangleAnnotation{    public object Content    {        get { return GetValue(ContentProperty); }        set { SetValue(ContentProperty, value); }    }    // Using DependencyProperty as the backing store for TextString.  This enables animation, styling, binding, etc...    public static readonly DependencyProperty ContentProperty = DependencyProperty.Register("Content", typeof(object), typeof(CustomTextAnnotation), new PropertyMetadata(null));    protected override void SetBindings()    {        base.SetBindings();  //You need to invoke this method to make all the default bindings        if (TextElement != null)        {            Binding textBinding = new Binding { Path = new PropertyPath("Content"), Source = this };            //TextElement is content control define internally to display text.            TextElement.SetBinding(ContentControl.ContentProperty, textBinding);        }    }}

<chart:SfChart  x:Name="chart" Margin="10" >    <chart:SfChart.PrimaryAxis>        <chart:CategoryAxis/>    </chart:SfChart.PrimaryAxis>    <chart:SfChart.SecondaryAxis>        <chart:NumericalAxis/>    </chart:SfChart.SecondaryAxis>    <chart:SfChart.Annotations>        <local:CustomTextAnnotation X1="1.6" X2="2.4" Y1="17.8" Y2="20.3" HorizontalTextAlignment="Center"                                     VerticalTextAlignment="Center" CanDrag="True" CanResize="True" x:Name="annotation">            <local:CustomTextAnnotation.Content>                <StackPanel Orientation="Horizontal">                    <Path Data="M16.710899,36.727C20.7409,39.759457 25.747499,41.558827 31.1693,41.558827 36.588501,                          41.558827 41.596401,39.759457 45.627602,36.727 55.046902,37.911882 62.335999,                          45.946764 62.335999,55.688923L62.335999,64 0,64 0,55.688923C0,45.946764,7.2904,37.911882,                          16.710899,36.727z M31.169201,0C40.807137,0 48.622002,7.8164558 48.622002,                          17.455803 48.622002,27.095258 40.807137,34.909003 31.169201,34.909003 21.528767,                          34.909003 13.715,27.095258 13.715,17.455803 13.715,7.8164558 21.528767,0 31.169201,0z"                           Stretch="Uniform" Fill="#606060" Height="49" Width="49"/>                    <TextBox Text="Employee:Jack Profit:16%" x:Name="textBox" Height="49" BorderBrush="Transparent"                             TextWrapping="Wrap" FontSize="15" HorizontalContentAlignment="Center"                              VerticalContentAlignment="Center" Foreground="Black" Background="Transparent" Width="105" />                </StackPanel>            </local:CustomTextAnnotation.Content>        </local:CustomTextAnnotation>    </chart:SfChart.Annotations>    <chart:ColumnSeries ItemsSource="{Binding Collection}" XBindingPath="XValue" YBindingPath="YValue"/></chart:SfChart>

Output: