here is a pure XAML approach
<TextBlock xmlns:ref="clr-namespace:System.Reflection;assembly=mscorlib">
<TextBlock.Text>
<Binding Path="Version">
<Binding.Source>
<ObjectDataProvider MethodName="GetName">
<ObjectDataProvider.ObjectInstance>
<ObjectDataProvider MethodName="GetExecutingAssembly"
ObjectType="{x:Type ref:Assembly}" />
</ObjectDataProvider.ObjectInstance>
</ObjectDataProvider>
</Binding.Source>
</Binding>
</TextBlock.Text>
</TextBlock>
in this example we are leveraging the ObjectDataProvider
to retrieve the desired (executing or can say current) assembly followed by it's version.
ObjectDataProvider is quite useful for retrieving results from method calls.