We do movie nights or board game nights after the kids go to bed. We’ve played different video games together as well, like Mario & stuff on our switch, We do some kind of little snack together & just hangout. Put our phones in a different room and just focus on each other.
Honestly everything costs money, I've tried to do date night ideas that didn't cost money and it always costs something. We've bought drinks and snacks and did movie night, we have adult card/board games, we have a show that we watch together and we plan a night that we're gonna watch it, when my mom has our daughter we do mini dates out, like Starbucks or a restaurant and only do appetizers and drinks. I honestly want more ideas too
We are on a budget, but sometimes when the kids are asleep or away, we do sip and paint at home while listening to some music( i go to the dollar store get supplies, canvas and paints). Or we have a little picnic in the living room floor.