It is fairly simple actually. Having no evolution means that the gene pool does not change from generation to generation. This is a situation we call the Hardy-Weinberg equilibrium https://en.wikipedia.org/wiki/Hardy–Weinberg_principle
In order for that to happen it requires certain conditions to be satisfied, such as infinite population size, entirely random mating, no mutations etc.
These are obviously not true for human, or in fact almost all populations. In other words, evolution is the normal situation and having no evolution is in fact an extraordinary claim. How would you, for example ensure that the next generation has the same genetic composition as the previous? Simple answer is, you cannot. What you might be thinking about are likely large-scale changes in visually obvious traits, but that is not what happens in the short time humans have been around. Rather, the level of phenotypic change you should be thinking about are things like, the shift in lactose tolerance, pigmentation. A fun study found that shift in folks growing up in the UK were an allele associated with higher nicotine dependency was weeded out because folks died young (due to high smoking habits). In populations where smoking was rare and also in modern times (again, fewer smokers) these alleles are becoming more frequent again (as selective pressure have lessened).
In short both theoretical as well as empirical evidence clearly demonstrate ongoing evolution and one might need to revise ones preconception of what evolution is to fully realize that.