It would be a surprise if we assume Iran does not acquire military technology from elsewhere. But to what extend and from where is the main question. Iranian military technology is based on several strategies:
1- Reverse engineering parts
2- Upgrading the reversed engineered parts or technologies.
The above is based on what is at Iran military disposal. So, where do these technologies come from.
1- From the Shah's time.
2- Captured from the wars (Lebanese wars included).
3- Arms purchased after revolution.
Now, we all know, very little arms trickled from the West to Iran through right out purchasing. But, some similar technologies were obtained from China, Russia, Pakistan and even North Korea. Much of eastern weapon technologies were of lower
standard than some similar technologies Iran held. As such, learning such technologies for reverse engineering did not take
a long time.
As a result of above and an excellent engineers the new upgraded weapon systems finally came to fruition. as you see now days. This may be why you suspect if Iran imports military hardware from the West.
In short, Iran imports very little or if any Western technologies directly. But Iran may be importing some small scale technologies
mainly for benchmarking or technology transfer.
For example, IRIAF claimed, three years ago, that it had obtained some latest NATO jamming pods for its fleets. How, no one knows. But I would not be surprised if this particular import assisted IRIAF's own home-built jamming pod.
Another example would be the fallen American UAV's in Iran either shot downed or failed ones. but my biggest suspicion is that Iran must have obtained a good deal from Iraq after US invasion. There were, for example, stories that Iraqis were selling damaged US and Iraqi tanks to Iran as "scrap".
Hope this will at least partly answer your question.