Considering HubSpot’s certifications are free and “open book” (meaning that you can reference materials as you take the test) the value in the job market is, in my experience, negligible. HubSpot certifications are most useful when training your own personnel.
By comparison, Marketo or Salesforce certifications are always proctored and will cost you about $200. Also, both Marketo and Salesforce Marketing Cloud are complicated systems, increasing the need for trained professionals. HubSpot is far easier to get a hold of, and also offers decent support (try and get a hold of Marketo or Pardot support and see if you get any kind of a decent answer to your question – good luck).
Now, that being said and having previously owned 5 HubSpot certifications, I *did* actually get some work based off of that. But it was (obviously) limited to HubSpot customers that needed help with specific issues.
So, long story short, I wouldn’t bother with the HubSpot inbound certification if a job is what you’re looking for.