The suspect, whose identity has not been revealed, is believed to be a courier who transported the package, reported 7news.com.au.
They allegedly took the iPhone from Hefei, in central China, to Shanghai, according to Chinese state-run newspaper The Global Times.
The suspect allegedly stole the phone and replaced the parcel with the drink, the paper reports.
The disgruntled customer, from East China’s Anhui Province, shared the discovery on Chinese social media app Weibo on Friday.
She said she didn’t directly receive the package from the courier and it was left in a parcel locker inside her residential community.
An Express Mail Service customer service staffer and an Apple spokesperson told the newspaper the incident was under investigation.
Local police earlier said it appeared to be a case of theft.