Almost.
You will still need a bar to hang from. Unfortunatly gravity only works one way an so its pretty tricky to work your Lats (the muscle that pull your arms down) with any weights.
If you have a bench it will also be easyer.
with dumbbells you can so squats, lunges, step ups, crunches, twisting crunches, shoulder press, reverse woodchoppers, bench press and bent rows.