Our main use case for HackerOne is to create a bridge between the organization and a global community of ethical hackers where we ask them to find bugs in our environment, and based on that, they provide us the bugs we have.
A quick example of how I've used HackerOne is that it provides us bug bounty programs and vulnerability disclosure programs where multiple bug bounty hunters submit their findings about the organization, and those vulnerabilities or bugs are fixed by us. For instance, we received many alerts about expired or mismatched SSL certificates.
We utilize HackerOne's web page where we log in to see what vulnerabilities are there and what else has been discovered, and based on that, we pick and work on the issues we need to fix.