Fuel injectors do make a noise, but it would usually be described as a “buzzing” rather than a “ticking”. If you could figure out a way to remove the injectors from the engine but keep them hooked up to the fuel rail and electrical connectors, aim them at a container to catch the gas, and get them to go into inject mode while the fuel pump was running, then you’d know for certain. There is a way to do that probably, but it may require some special test equipment most diy’ers wouldn’t have. I’ve done that experiment with a 70’s VW Rabbit (K-Jetronic mechanical fuel injection), and yes, those injectors did make quite a racket in that configuration. But like I say, it was more of a high pitched buzzing noise.
@Bing’s unplugging idea above makes sense as a compromise test. By “unplugging” I guess Bing means to unplug the electrical connection to the injector so it won’t pulse, not unplugging (removing) the injector from the engine intake manifold.
If it isn’t the injectors, probably time for a valve clearance measurement. You may just have a couple of loose valves on your hands needing adjustment.