Hyperlinkタグに「RequestNavigate = "Hyperlink_RequestNavigate"」を入れる
hyperlink.xaml
<TextBlock>
<Hyperlink NavigateUri = "https://www.yahoo.co.jp/"
RequestNavigate = "Hyperlink_RequestNavigate">
こちら
</Hyperlink>
</TextBlock>
参考:
https://www.366service.com/jp/qa/be8bff473a3a9f570c9a7021e8a00922