@ivan_zenkovich through social media and content marketing, paid ads, referral programs, App Store Optimization. There are some tips on this site (I'm not affiliated or write for this site) https://iterable.com/blog/top-5-...
I recommend you to check out the question part of producthunt, to see if some are relevant for your product.
Google "keyword + site:https://www.producthunt.com/ask" to check it out. If you are interested I have a prototype of data miner to do this at scale.
Get feedback from everyone that signed up from your PH launch. Monitor if they continue using your product or not. If they are that is great (congrats), if not find out why.