Okay, let's do this!

For military history (which is highly relevant to Cyrus, considering his conquests), look at these two:

https://www.amazon.com/Shadows-Desert-Ancient-General-Military/dp/1846031087/ref=sr_1_1?dchild=1&keywords=Shadows+in+the+desert&qid=1605335559&sr=8-1

https://www.amazon.com/Armies-Ancient-Persia-Founding-Achaemenid/dp/1945430087/ref=sr_1_2?dchild=1&keywords=Achaemenid+army&qid=1605335585&sr=8-2

For general Achaemenid history, look at these:

https://www.amazon.com/Ancient-Persia-Matt-Waters/dp/0521253691/ref=pd_sbs_14_2/130-0287650-0898208?_encoding=UTF8&pd_rd_i=0521253691&pd_rd_r=0d5319e0-3ddd-4ab5-8668-ecd3d3617a44&pd_rd_w=zcKIW&pd_rd_wg=RKwRZ&pf_rd_p=52ff3488-8ecd-4341-9663-52e4fb00f500&pf_rd_r=7PKPAN4RJM28Z8XZWCW1&psc=1&refRID=7PKPAN4RJM28Z8XZWCW1

https://www.amazon.com/Cyrus-Alexander-History-Persian-Empire/dp/1575060310/ref=pd_sbs_14_4/130-0287650-0898208?_encoding=UTF8&pd_rd_i=1575060310&pd_rd_r=0d5319e0-3ddd-4ab5-8668-ecd3d3617a44&pd_rd_w=zcKIW&pd_rd_wg=RKwRZ&pf_rd_p=52ff3488-8ecd-4341-9663-52e4fb00f500&pf_rd_r=7PKPAN4RJM28Z8XZWCW1&psc=1&refRID=7PKPAN4RJM28Z8XZWCW1

Hope these help!

Excellent question, with more answers than I think you really want. u/ByzantineBasileus hit the two surveys that everyone should have a look at. Ancient Persia by Matt Waters is brief and concise and From Cyrus to Alexander by Pierre Briant is still the definitive book on Achaemenid Persia. I have a few more recommendations.

Discovering Cyrus by Reza Zarghamee. Assuming you mean Cyrus the Great, this is the book.

The Persian Empire: A Corpus of Sources from the Achaemenid Period by Amelie Kuhrt. This is an invaluable collection of primary sources for the Persian Empire with commentary.

Encyclopaedia Iranica is a free, online, academic encyclopedia for all parts of Iranian history, including the Achaemenids.

I also maintain a much larger list the most useful books for ancient Persia on my website