The Leeds United loanee netted in each half as John Schofield’s players ran out 4-0 winners at the Ballymena Showgrounds.
McCalmont opened the scoring with a first-time finish after Paddy Lane’s ball in was helped across the box by Ryan Waide.
Paul O’Neill doubled the lead before half-time, after which McCalmont netted again from close range, while Chris Conn-Clarke completed the scoring.
Another of Morecambe’s internationals, Reading loanee Jokull Andresson, was on the bench as Iceland’s U21s won 3-0 in Liechtenstein.
Northern Ireland’s U21s are back in action against Malta on Tuesday (7.30pm), while Iceland travel to Greece (2pm).
As for the Shrimps’ other international Greg Leigh, Jamaica’s World Cup qualifier against El Salvador kicks off at 2.05am UK time on Saturday.
That will then be followed by another qualifier against the USA, also on Tuesday, beginning at 10pm UK time.
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