The pop stars posed with the producer Andrew Watt, who has worked with artists including Justin Bieber, Selena Gomez and Cardi B.
Cyrus, 27, captioned the photo: “Dua has heard what you haven’t…”
Future Nostalgia star Lipa, 24, posted a similar photo with the caption “bromance” while Watts appeared to point towards the style of the song, adding: “Warm…warmer…DISCO!!!”
Fellow stars including Demi Lovato shared their excitement at the prospect of new music from Cyrus.
She commented: “Wow I’m not ready.”
Cyrus’s post came hours after she released a short clip of an unreleased track titled Midnight Sky via her Instagram page.
Former Hannah Montana star Cyrus’s last album was 2017’s Younger Now, which contained the single Malibu.
She is currently working on her seventh studio album, tentatively titled She Is Miley Cyrus.
It will be the first full-length since her divorce from Liam Hemsworth earlier this year.
She met the Australian actor on the set of romantic drama The Last Song in 2010 and dated on and off for nearly a decade before tying the knot in 2018.
Cyrus and Lipa have previously worked on songs together, even finishing a track shortly before the coronavirus pandemic.
However, the pair decided not to release the final product.