I interpret your question as one about intelligence officers of countries other than Russia, who were recruited as spies by CheKa and its successors (GPU, OGPU) prior to 1921/1926.
At least in Great Britain, the earliest known case is the one of Wilfried F. R. Macartney, see Security Service Records Release 14 November 2001 :
Wilfred Macartney and George Hansen, KV 2/647-656. Macartney was a British
army intelligence officer who led a Soviet spy ring. In 1917 he was assigned to
the officer in charge of intelligence activities in the Eastern Mediterranean, Capt. Compton Mackenzie. In 1926 he was brought to the attention of MI5 through a Lloyds underwriters employee who had been given £25 by Macartney and asked to provide information about the RAF for the Soviets. A trap was set and a faked secret RAF manual was passed over. On the basis of this Special Branch were instructed to raid ARCOS Ltd., which was linked with the Soviet Trade Delegation (see ARCOS above). The RAF manual was not recovered but the government severed diplomatic relations with Russia nevertheless. Macartney was briefly left at liberty in the hope that he would lead the authorities to Soviet agents but this came to nothing and Macartney was convicted and given a 10-year jail sentence. He later served with the International Brigade during the Spanish Civil War. Georg Hansen, a German, was convicted along side Macartney and also received a 10 year sentence he was however, deported to Russia in 1935 (KV 2/649-656).