In a medium bowl, combine the softened cream cheese, fresh dill, lemon juice, and chopped capers. Mix until smooth and well blended.
Lay out the cucumber slices on a serving platter. If using baguette slices, arrange them in a single layer.
Spread a generous amount of the cream cheese mixture on each cucumber slice or baguette slice.
Top each spread with a piece of smoked salmon, folding it if necessary to fit.
Sprinkle a small amount of red onion on top of the salmon for added flavor.
Garnish each bite with a sprig of fresh dill.
Serve immediately or refrigerate for up to 30 minutes before serving for a chilled option.