Nope! There are plenty of things you can find around the house or outside to use instead of dumbbells.
1-2 lb. objects: Great for Align class!
~10 Forks or spoons tied together with a rubber band will give you between 1-2 lbs. depending on how heavy your set is! This option gives you a nice grip!
16 oz. water bottle is about 1 lb./ 32 oz water bottle is 2 lbs.
1 lb. bag of coffee also provides a nice grip, just please, make sure it's closed!
Fill an old pair of socks with 1 cup (each) or more of pebbles/rice/sand for another comfy dumbbell option. 1 cup will roughly be 1 lb.
5 lb. objects:
72 oz. laundry detergent bottles with handles. Save your empties and fill them with water!
Fill a reusable shopping bag with 5-6 cans of beans or soup.
Put 2 textbooks in a backpack for about 6 lbs. (think of the "average textbook" for size)