It's hard to answer that question - indeed, it's not clear that it really makes sense to ask it.
The difficulty is that sounds in spoken language are not nearly as clear-cut as you might think. A pertinent question is not "can you hear that sound?" but "can you distinguish these two sounds?"
Consider the English words kill, skill, cool, and school. To English ears, they all have the same /k/ sound; and indeed in transcribing them in IPA, we would normally write them all with the same /k/: /kɪl/, /skɪl/, /ku:l/,/sku:l/.
But actually, the /k/ sound is phonetically different in all four cases (it is aspirated in kill and cool, and palatalised in kill and skill: /kʲʰɪl/, /skʲɪl/, /kʰu:l/,/sku:l/) - and to speakers of some languages they would be different sounds, and would be transcribed differently.
So, while it is true that most languages (not all!) have at least one unvoiced velar plosive, broadly transcribed /k/, some have several, all corresponding to English /k/.
So is /k/ universal? English speakers generally can't distinguish it from /kʰ/, and can't pronounce it except after /s/. So maybe it's /kʰ/ that's universal? But some languages don't have that variant at all.