Extract dynamic code from a WMT URL

Summary:

Hello,
I have a property (example: URL_WMT) that captures the WMT URL.
Full URL: https://w.etadirect.com/a784hk596
Dynamic part: a784hk596
I need to extract only the dynamic part to send it via a message scenario. How can I do this? By using a new property and a message scenario?

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