Legally or physically?

Unfortunately, the reality is that you just have to assume that everyone who has access to your code has a copy of it on their home PC. They probably don't, but there's very little that you can do to stop them if they wanted to. Think of it this way - have you ever met someone in sales who didn't have a copy their rolodex and some good sample contracts at all times?

The "good" news here is that just having IP is not enough. Software development is so fast and efficient these days that even starting with code, unless you have some very particular formulae (and if you do you should keep them somewhere else with limited access to that code), most of your code is not particularly relevant. To anyone wishing to compete with you its probably fairly simple to copy your product, but much harder to copy the business itself. If you have reasonable employment agreements you can probably make the risk of copying greater than the benefit that a new competitor would get by doing so, and that's often the best you can do.

That's both a blessing and a curse. I've started a few successful "product" companies that relied on SaaS software and would be happy to discuss it further if you like.