Better, with regards to Unicode (and after all, this is what UCS2 is about):

sub UCS2 { return join '', map { sprintf "%04X", ord } split //, $_[0]
+ }
print UCS2 ("Hello\x{1234}");
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Result:

00480065006C006C006F1234
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As you can see, it works flawlessly with characters with a character code above 255.