Scholars have written much about this issue. Here is the summary of A. Van der Heide:
The origin of the acronym Pardes can be established with some
precision. Following the initial research carried out by W. Bacher,
Gershom Scholem convincingly traced the invention of the highly
evocative pun to Moses de Leon... In all probability it was introduced
by Moses de Leon in a book called Sefer ha-Pardes, which he mentions
in at least two places. The book itself is not extant. The idea found
its way to the later parts of the Zoharic corpus, the Ra'ya Mehemna
and the Tiqqune Zohar, and from there is spread to other works.
Gershom Scholem in his article “The Meaning of Torah in Jewish Mysticism” in On the Kabbalah and Its Symbolism (New York: Schocken, 1996), 32-86, noted that the development of a fourfold hermeneutical method appeared simultaneously in the works of R. Moshe de Leon, R. Yosef Gikitilla and R. Bachya b. Asher. The description “Pardes” for this fourfold interpretation belongs to R. Moshe de Leon, in a lost work of that name, and became widely known through the Tikkunei Zohar.
See also M. Idel, “Pardes: The Fourfold Method of Interpretation” (Appendix I) in Absorbing Perfections: Kabbalah and Interpretations (New Haven, Conn.: Yale University Press, 2002), pp. 429-37. Idel argues that the tiered “Pardes” hermeneutic allowed Kabbalists to locate kabbalistic interpretation in “a place of honor” without replacing existing methods of exegesis. According to late thirteenth century kabbalists, the “four who entered Pardes” each reached one level of PaRDeS. Likewise, Pardes was seen to correspond to four worlds of ‘atzilut, beriah, yetsirah and ‘asiyah. The kabbalist climbs successively through these worlds by means of the pardes method.
B. Sack, The Kabbalah of R. Moshe Cordovero [Hebrew] (Jerusalem: Bialik Institute, 1995) pp. 113-139, discusses the view of R. Moshe Cordevero, according to which the four levels of souls correspond to the four levels of understanding Torah, PaRDeS, and the four worlds.