Black Holes are yet to be observed
Many of us might be with the wrong information that we have already observed Blackholes, but we haven't till today. As we know, Blackholes are celestial objects with massive gravitational force, where even the light cannot escape.
These Blackholes are not observed yet, the Gravitational wave that was detected a year ago in LIGO was a prediction of two merging blackholes, this has ensure the existence of Blackholes, but they are yet to be directly observed by our technology, eye and mind.
To do this, currently we are making an effort to build an event horizon telescope, which would use radio telescopes to directly observe the shadow cast by our very own Milky Way’s supermassive black hole, Sagittarius A*. If this is successful we will be observing the blackholes for the first time. This will be the next big day of our evolution.
LIGO observations are very well explained by the merging of two black holes, and there is so far no alternative hypothesis that explains the detected gravitational waves as good.
However, you are right and this only consists of an indirect probe. Concerning direct observation, we are far from being there. The Chandra observatory collected a bunch of data a couple of years ago. The EHT telescope that combines the strengths of several existing observatories gives good hopes to learn more in the future.
If you allow me, I would add this reference to your post, so that other readers could find more information.