Weird occurrences happening in my new apartment

Hello this is my first time posting on reddit but I need some advice on some weird things going on in my apartment. I am not a good writer at all so sorry if it is hard to understand. So me, my sister and my friend just moved into a new apartment 2 weeks ago. The first week nothing strange had happened, but my sister and friend told me about something that happened earlier today and a couple days ago. My sister and friend were at the pool all day at our apartment today while I was at work. When I got home from work I sat in my car in the apartment parking lot on my phone for about 45 minutes. While I was in my car my sister called me and asked me if I had gotten home from work yet. I told her no I was sitting in my car. Then when I got inside she told me that her and our friend had gotten back from the pool about an hour before I got home and both were taking a shower at the same time in their separate bathrooms. My sister told me that when she was in the shower she heard what sounded like someone trying to open her bathroom door. Usually when she’s in the shower and one of us needs to go in and it’s locked we’ll pick the lock because it is one of those penny locks you can easily pick. So when she heard that she yelled to pick the lock and come in. She told me she just kept hearing the doorknob moving and she yelled a couple more times before it sounded like it was trying to pick the lock then stopped. Noone else was home except our friend who was also in the shower. Then our friend said the when she was in the shower she heard a girls voice talking to my cat. She said she assumed I had gotten home and was talking to my cat because usually when I get home my cat is at the door and i say hi to her. She said she heard something like “Oh look there is the baby” and “hi baby” I call my cat baby and talk to her like that so that’s why she thought it was me. She said the voice sounded like mine but as if I was tired. She said she also just kept hearing a conversation presumably to my cat but ignored it because she thought it was me. I know for sure I was not home at the time because when I got home the door to my apartment was locked and they weren’t there. They had gone to the store before I went inside. They told me they had left the door unlocked while they were in the shower but what confuses me is since we just moved only like 3 of our friends know where we live now and we know they weren’t here. We thought maybe that someone had come inside and done weird stuff but nothing was missing or anything. It is also weird because whoever that was talking to my cat exactly how I talk to her. We can’t think of any explanation for this. They also told me about how a couple days ago They saw 2 Icee cups in the parking lot and where complaining about littering and people leaving those cups in the parking lot then later that day the cups were outside our apartment door???? Should we get cameras? I have no clue what happened today could’ve been. I also forgot to add that they told me after that had happened in the showers that they searched the whole apartment and didn’t find anything. I really believe that they aren’t messing with me because they actually seem really freaked out about it and won’t go to any rooms by themselves. I have no clue what is going on. Any advice would be sooo appreciated.